An electrical connector is frequently used to terminate a multi-conductor electrical cable. The electrical connector may be either a male or female plug or receptacle, and the conductors of the multi-conductor electrical cable are terminated to contacts of the electrical connector. This connector is arranged to electrically mate with a corresponding connector of an electrical apparatus. Furthermore, a connector adapter, such as a backshell having a backshell body and a coupling ring, is frequently used in combination with an electrical connector and its associated multi-conductor electrical cable. The coupling ring of the backshell is arranged to couple the backshell body to the electrical connector.
Backshells are formed in various configurations, such as elbows, and are arranged to perform one or more various functions, depending upon their particular application. In an example of one application, electrical connectors having backshells coupled thereto are used extensively for the interconnection of an aircraft's various control and/or instrumentation functions. This application requires such electrical connectors to be shielded from electromagnetic interference and to withstand substantial dynamic forces such as those arising from vibration, shock, bending, and temperature cycling. If electrical connectors are not properly shielded, electromagnetic interference can result in undesirable and potentially dangerous disruptions of the control and/or instrumentation functions of an aircraft. Similarly, if strain relief is not provided, dynamic forces can cause strain on the electrical conductors which, in turn, can cause dislocation of the pins of the electrical connectors resulting in a disruption or loss of an aircraft's control and/or instrumentation functions. Backshells have been arranged to provide electromagnetic interference shielding and strain relief for such electrical connectors and conductors.
The coupling ring and the backshell body of a typical backshell are arranged so that the coupling ring is held captive to the backshell body. Accordingly, once the backshell is assembled, the coupling ring cannot easily be removed from the backshell body. The backshell may be provided with an anti-rotation device in order to prevent rotation between the backshell and the electrical connector to which it is coupled. The backshell may also be provided with an anti-rotation mechanism between the backshell body and the coupling ring.
Unfortunately, if a typical prior art backshell is improperly seated against a corresponding electrical connector, the backshell can disengage from the electrical connector. If the backshell disengages from the electrical connector, dynamic forces can cause the backshell to move and twist with respect to the electrical connector permitting dislocation of pins of the electrical connector. If the pins dislocate, these pins may break the electrical connection between the electrical connector and a corresponding electrical connector to which it is coupled. Also, electromagnetic interference can propagate between the backshell and the electrical connector and can intrude into the interior of the backshell where it may interfere with the electrical signals carried by the electrical connector.
Precautions have been taken in the past in order to preclude such unintentional relative movement between the backshell and its corresponding connector. For example, safety wires have been attached to both the coupling ring of the backshell and the corresponding electrical connector, and are intended to lock the backshell to the electrical connector so that relative movement therebetween is prevented. Set screws and thread locking compounds have also been used between the backshell and its corresponding electrical connector in order to prevent such relative movement. These arrangements, however, increase the cost of manufacturing and installing electrical fittings.
Moreover, even though the correct amount of coupling torque is applied by an installer to the coupling ring of a prior art backshell, this backshell may be improperly seated against its corresponding electrical connector. Consequently, the installer may falsely believe that the backshell is properly seated because the coupling "feels" tight (i.e., the installer applied the correct amount of coupling torque to the coupling ring). However, because the backshell and the electrical connector are improperly seated against one another, the coupling between the backshell and the electrical connector can loosen. If this coupling loosens enough, the backshell may no longer provide the necessary shielding thereby allowing electromagnetic interference to intrude into the backshell and interfere with the electrical signals carried by the connector. This interference can disrupt the control and/or instrumentation functions of the electrical apparatus to which the electrical connector is connected. Also, the pins of the electrical connector can dislocate sufficiently to disrupt these control and/or instrumentation functions.